Fuel Gauge Stuck!
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Mountain Pass
Joined: May 2003
Posts: 200
Likes: 26
Fuel Gauge Stuck!
I have 2005 F50 PSD 6.0 Lariat. Went this evening to fill up. It took 26.6 gallons which is the most I have ever put in since owning the truck. When I started the truck, the fuel gauge stayed down well below the 1/4 tank level. After driving a couple miles, it crept up close to 1/4 tank, but the computer still said 49 miles to empty and was giving me the low fuel warning. Any ideas of what to check? I am guessing sending unit?
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Mountain Pass
Joined: May 2003
Posts: 200
Likes: 26
After Google search - I found this:
my fuel gauge on my 2005 f250 quits working when driving--is - JustAnswer
my fuel gauge on my 2005 f250 quits working when driving--is - JustAnswer
Cargo Master
Joined: Mar 2007
Posts: 3,103
Likes: 32
From: AB/BC
Our Fuels: Fuel Additives: Techron Concentrate Plus I have never used this but it's suppose to be very good.
Logistics Pro
Joined: May 2004
Posts: 3,608
Likes: 870
Liv is correct. When fuel was 5.00+ in CA I filled up a 1/4 tank at a time since I live soooo close to work. I had to fill my truck for a trip (160.00+). My gauge read 1/4 for about 3 days. I assumed what happened was since the float mechanism was not in a consant fuel bath it probably began to rust limiting it's travel.
Worse case your float is no good....I doubt it though. Keep it full and it should return to normal.
Worse case your float is no good....I doubt it though. Keep it full and it should return to normal.
Thread Starter
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Mountain Pass
Joined: May 2003
Posts: 200
Likes: 26
Well, by the time I drove 8 miles to work it almost made its way up to full. By noon is was where I expected needle should be. Still wonder what would have cause it - other than the fact that it was the lowest the tank had ever gotten.
Posting Guru
Joined: Dec 2006
Posts: 1,078
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From: Kansas City/Breckenridge
like I said before
search is your friend...
its in the tech folder the sticky at the top of our forum
search is your friend...
its in the tech folder the sticky at the top of our forum
Fuel Gauge
The instrument cluster receives the fuel level signal from the fuel level sensor, part of the fuel tank unit. The fuel level sensor measures variable resistance in the fuel tank depending on the current fuel level. When the fuel level is low, the resistance in the unit is low (15 ohms ± 2 ohms). When the fuel level is high, the resistance in the unit is high (160 ohms ± 4 ohms).
The instrument cluster uses 4 different operating modes to calculate the fuel level:
anti-slosh (default mode)
key OFF fueling
key ON fueling
recovery
After a fuel fill up, the time for the fuel gauge to move from empty (E) to full (F) ranges from 2 seconds to 55 minutes depending on which operating mode the fuel gauge is in.
The default fuel gauge mode is called the anti-slosh mode. To prevent fuel gauge changes from fuel slosh (gauge instability due to changes in fuel sender readings caused by fuel moving around in the tank), the fuel gauge takes approximately 55 minutes to go from full (F) to empty (E).
The key OFF fueling mode (2 seconds to read empty [E] to full [F]) requires 3 conditions be met:
The key must be in the OFF position when refueling the vehicle.
At least 15 percent of the vehicle's fuel capacity must be added to the fuel tank.
The instrument cluster must receive a valid key ON fuel sender reading within 1 second of the key being put into the RUN position. The key ON sample readings are considered valid if the fuel sender reading is between 15 ohms ± 2 ohms and 160 ohms ± 4 ohms. If these conditions are not met, the fuel gauge stays in the anti-slosh mode, which results in a slow to read full (F) event.
The key ON fueling mode (approximately 90 seconds to read empty [E] to full [F]) requires 3 conditions be met:
The transmission is in park (P) (automatic transmissions), or the parking brake applied (manual transmissions).
The key is in the RUN position.
At least 15 percent of the vehicle's fuel capacity must be added to the fuel tank.
In key ON fueling mode, a 30 second timer activates after the transmission is put into the park (P) position (automatic transmissions) or when the parking brake is applied (manual transmissions). When the 30 second time has elapsed and at least 15 percent of the vehicle's fuel capacity has been added, the fuel gauge response time is 90 seconds to read from empty (E) to full (F). When the transmission is shifted out of park (P) or the parking brake is released, the fuel gauge strategy reverts to the anti-slosh mode. This mode prevents slow to read full events from happening if the customer refuels the vehicle with the key in the RUN position.
Recovery mode is incorporated into the instrument cluster strategy to recover from a missing fuel level message during a refueling event. Missing fuel level messages result from intermittent opens in the fuel sender or its circuits. Recovery mode (empty [E] to full [F] approximately 20 minutes) is initiated when the following 2 conditions are met:
The instrument cluster is in the anti-slosh (default) mode.
The actual fuel level in the tank is greater than what is being displayed by the fuel gauge.
The instrument cluster receives the fuel level signal from the fuel level sensor, part of the fuel tank unit. The fuel level sensor measures variable resistance in the fuel tank depending on the current fuel level. When the fuel level is low, the resistance in the unit is low (15 ohms ± 2 ohms). When the fuel level is high, the resistance in the unit is high (160 ohms ± 4 ohms).
The instrument cluster uses 4 different operating modes to calculate the fuel level:
anti-slosh (default mode)
key OFF fueling
key ON fueling
recovery
After a fuel fill up, the time for the fuel gauge to move from empty (E) to full (F) ranges from 2 seconds to 55 minutes depending on which operating mode the fuel gauge is in.
The default fuel gauge mode is called the anti-slosh mode. To prevent fuel gauge changes from fuel slosh (gauge instability due to changes in fuel sender readings caused by fuel moving around in the tank), the fuel gauge takes approximately 55 minutes to go from full (F) to empty (E).
The key OFF fueling mode (2 seconds to read empty [E] to full [F]) requires 3 conditions be met:
The key must be in the OFF position when refueling the vehicle.
At least 15 percent of the vehicle's fuel capacity must be added to the fuel tank.
The instrument cluster must receive a valid key ON fuel sender reading within 1 second of the key being put into the RUN position. The key ON sample readings are considered valid if the fuel sender reading is between 15 ohms ± 2 ohms and 160 ohms ± 4 ohms. If these conditions are not met, the fuel gauge stays in the anti-slosh mode, which results in a slow to read full (F) event.
The key ON fueling mode (approximately 90 seconds to read empty [E] to full [F]) requires 3 conditions be met:
The transmission is in park (P) (automatic transmissions), or the parking brake applied (manual transmissions).
The key is in the RUN position.
At least 15 percent of the vehicle's fuel capacity must be added to the fuel tank.
In key ON fueling mode, a 30 second timer activates after the transmission is put into the park (P) position (automatic transmissions) or when the parking brake is applied (manual transmissions). When the 30 second time has elapsed and at least 15 percent of the vehicle's fuel capacity has been added, the fuel gauge response time is 90 seconds to read from empty (E) to full (F). When the transmission is shifted out of park (P) or the parking brake is released, the fuel gauge strategy reverts to the anti-slosh mode. This mode prevents slow to read full events from happening if the customer refuels the vehicle with the key in the RUN position.
Recovery mode is incorporated into the instrument cluster strategy to recover from a missing fuel level message during a refueling event. Missing fuel level messages result from intermittent opens in the fuel sender or its circuits. Recovery mode (empty [E] to full [F] approximately 20 minutes) is initiated when the following 2 conditions are met:
The instrument cluster is in the anti-slosh (default) mode.
The actual fuel level in the tank is greater than what is being displayed by the fuel gauge.
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Thread Starter
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Mountain Pass
Joined: May 2003
Posts: 200
Likes: 26
Thanks for the tech notes. Now I need to research more to see if I can diagnose the problem further. Now the fuel gauge is stuck on Full. I have driven 71 miles and it has not moved a bit.
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Joined: Jul 2005
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Chas, I had a fuel gauge issue that took 20,000 miles or so to figure out. The gauge would drop to empty when full, or not show full when filled up (for days). The stealership tried Techron, new fuel sender assembly, you name it. They finally discovered that the instrument cluster was the problem and replaced it under warranty. Probably not what you are dealing with, but I thought I would pass along my experience, it might help.
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Mountain Pass
Joined: May 2003
Posts: 200
Likes: 26
Interesting that you mention instrument cluster...I have another post that deals with windows & radio not working when the truck is first started. Ford has no resolution at all for that. Left my truck at dealer for stints of 3-4 days and of course problem would not duplicate for them. I had a forum member email me and said he was a dealership and had a truck with same problem. They replaced the instrument panel and it took care of the window/radio delay problem. So instrument panel issues is not out of the question I suppose (rather than thinking it is a fuel sender unit problem, etc)
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